The present invention generally relates to rolling element bearings and, more particularly, to removal features and removal tools for rolling element bearings.
Rolling element bearings have been used extensively in many products such as engines, transmissions, drivetrains, gearboxes, and machine tools. Rolling element bearings may comprise inner and outer bearing rings and bearing balls or rollers there between. The rolling element bearing may be positioned within the product such that the inner diameter of the rolling element bearing is in contact with a bearing shaft. The rolling element bearing may be removed for product disassembly or bearing replacement. Removal methods and removal tools have been described.
Ball bearing pullers that grip an outer diameter edge of the bearing assembly have been used. For a bearing assembly having an inaccessible outer edge, crude methods of removal have included destruction of the bearing with torches, grinders, and chisels. For some applications, these destructive methods may not be desirable and other methods have been disclosed.
A ball bearing puller attachment has been disclosed in U.S. Pat. No. 4,916,791. In the described removal method, links are positioned between the balls of the bearing assembly to grip the inner or outer raceway groove. The bearing assembly is then removed by axial force. For bearings that are interference (press) fitted onto a shaft, thrust overload may damage the bearing. Additionally, the gripping links will damage the bearing raceway rendering the bearing not reusable. Further, the described tool is not useful for bearings having ball separators because the links must fit between the balls to engage the outer race.
Another removal tool has been disclosed in U.S. Pat. No. 6,088,898. The described method positions wedge shaped insertion edges behind the bearing outer races or sleeves press fitted into a housing. The tool requires the bearing to be disassembled with only the outer ring remaining in the housing. Damage to parts may occur due to the high radial forces needed to drive the wedges behind the bearing race/sleeve. Although, the described tool may be used to remove some bearing outer races, it is not useful for bearing assemblies having the inner ring press-fitted onto a shaft. Further, the use of a slide hammer to exert axial force may result in part damage for some applications, such as aerospace bearings.
A removal tool using a threaded shaft (jackscrew) to exert axial force has been disclosed in U.S. Pat. No. 5,255,435. The tool uses a mandrel having drive shoulders to engage the bearing. Although, the tool may be used to remove a press-fitted bearing inner ring or outer ring, it cannot engage and remove a complete bearing assembly. Only a single press-fitted inner or outer ring can remain to allow tool access. Additionally, the shoulders may damage the functional raceway surfaces, rendering the bearing not reusable. The tool cannot engage and safely remove an entire bearing assembly, such as a non-separable conrad ball bearing or a split-inner ring ball bearing, with no damage to the raceways or functional surfaces.
A method for removing an entire bearing assembly has included axially extending the bearing inner ring. A puller groove removal feature is provided on the outward surface (outer diameter) of the extended portion of the inner ring to facilitate removal tool engagement. The disclosed method may be used to safely remove the entire bearing assembly when the inner ring is press-fitted to the shaft and when there is insufficient clearance to fit a removal tool around the outer diameter of the bearing assembly to engage the aft face for removal. Unfortunately, the extended portion of the inner ring adds weight and length to the bearing assembly, which in many designs must be minimized. On high speed rotor systems, such as some gas turbine rotors, excess mass and length can reduce rotordynamic critical speed margin and result in high vibration and bearing loads.
As can be seen, there is a need for improved bearing removal tools and removal methods. Additionally, improved removal methods are needed wherein the entire bearing assembly can be removed without damage to the parts. Bearing removal methods are needed wherein bearing inner ring weight and axial length are minimized. Improved removal tools are needed for removing bearings having ball separators. Further, improved bearing removal tools are needed for removing bearings having press-fitted inner rings and inaccessible outer diameter edges.